JPH07322156A - Diversity reception equipment - Google Patents

Abstract

PURPOSE:To prevent the occurrence or a break or sounds, step out or pictures, deturning, or the like by detecting a multipath signal or sounds in a certain wait time in combination of the video diversity operation where the antenna having the highest picture electric field level out of plural antennas is selected and successively switching the antennas till detection of no multipath signal. CONSTITUTION:Based on the vertical synchronizing signal of a received video signal, a timing controller 10 outputs a video diversity signal to an antenna switching controller 11 in the vertical blanking period. The antenna switching controller 11 outputs a switching signal to a changeover switch 2 based on this video diversity signal to successively switch four antennas 1a to 1d in the vertical blanking period. The multipath signal is detected in the middle of video reception by a multipath detection circuit 8, and an audio diversity signal is outputted to the antenna switching controller 11 through an audio diversity controller 9, and the switching signal is outputted to the changeover switch 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiving apparatus having a plurality of antennas and selecting one receiving antenna.

[0002]

2. Description of the Related Art When a television broadcast is received in a moving body such as an automobile, multiple interference fading occurs due to the influence of the terrain around the moving body, buildings and the like, which significantly deteriorates a received image. In order to solve this drawback, a mobile body is provided with a plurality of antennas, each antenna is switched for each vertical blanking period, and the electric field strengths (levels) received by the respective antennas are compared to determine the highest electric field level. A diversity receiver has been proposed in which a high antenna is selected and is connected to an input line of a television receiver. However, this type of diversity receiver
Since this is a so-called video diversity operation in which the best antenna is selected by focusing on the electric field level of only the received video signal, no consideration is given to the audio signal received with the video signal. That is,
The best antenna for a video signal does not always become the best antenna for an audio signal, and the best antenna may differ between video and audio due to a difference in modulation method, frequency, or the like. Therefore, when receiving a television broadcast, the received video may be prevented from being deteriorated, but the sound may be deteriorated. Therefore, there has been proposed a diversity receiver that also considers voice.

FIG. 10 is a block diagram showing an example of a conventional diversity receiving apparatus. When a multipath signal of voice is detected, voice mute is applied to remove noise and distorted sound. 51 is 4 for example
Antennas consisting of the books (51a, 51b, 51c, 51d), 52 is a changeover switch that arbitrarily switches the four antennas 51a to 51d, and 53 is a desired station selected from a signal received from any antenna via the changeover switch 52 Front end for converting to intermediate frequency (IF), 54
Is a video IF circuit that extracts and amplifies the video IF signal from the output of the front end 53, 55 is a video detection circuit that reproduces the video signal from the output of the video IF circuit 54, and 56 is an audio IF signal from the output of the front end 53 A voice IF circuit that amplifies and outputs the signal of the S meter that indicates the received electric field level, and a voice detection circuit 57 that reproduces a voice signal from the output of the voice IF circuit 56.

Reference numeral 58 is a multipath detection circuit for detecting a multipath signal from the output of the audio IF circuit 56, and 59 is a mute circuit for muting the output of the audio detection circuit 57 based on the output of the multipath detection circuit 58. Reference numeral 60 is a timing controller that extracts a vertical synchronization signal from the output of the video detection circuit 55 and generates a timing signal (video diversity signal) for antenna switching, and 61 is switched within the vertical blanking period based on the video diversity signal from the timing controller 60. An antenna switching controller that outputs a switching signal to the switch 52, and a video maximum electric field level detection circuit 62 that detects the video maximum electric field level from the output of the video detection circuit 55. With the above configuration, under the control of the timing controller 60, the antenna switching controller 61 is controlled by the video maximum electric field level detected by the video maximum electric field level detection circuit 62 to select the best antenna. When a multipath signal is detected by the multipath detection circuit 58 while the video signal is being received by the selected antenna, the mute circuit 59 is operated to operate the audio detection circuit 57.
Mute the output of. This makes it possible to remove noise and distorted sound based on the audio signal during reception of the video signal.

FIG. 11 shows another example of the conventional diversity receiving apparatus, in which the maximum electric field level antenna selection by video and the maximum electric field level antenna selection by voice are switched depending on the reception condition. . The same parts as those of FIG. 10 are denoted by the same reference numerals, and 63 is a voice maximum electric field level detection circuit for detecting the voice maximum electric field level from the output of the voice IF circuit 56. FIG. 12 shows FIG.
1 shows a specific configuration of the antenna switching controller 61 of No. 1, which switches a video maximum electric field level detected by a video maximum electric field level detection circuit 62 or a voice maximum electric field level detected by a voice maximum electric field level detection circuit 63. The maximum input antenna latch 64 stores the antenna for which this video or audio maximum electric field level is obtained, and the counter 65 that sequentially counts the antenna under the control of the timing controller 60. With the above configuration, antenna switching is performed based on the video maximum electric field level detected by the video maximum electric field level detection circuit 62 or the audio maximum electric field level detected by the audio maximum electric field level detection circuit 63 under the control of the timing controller 60. Control the controller 61 to select the best antenna. According to such a diversity receiving apparatus, the best antenna can be selected in consideration of not only video but also audio, so that it is possible to prevent deterioration of received video and audio.

[0006]

However, the conventional diversity receivers as described above have the following problems, respectively. (1) In the diversity receiver having the configuration shown in FIG. 10, when multipath is frequently generated, the sound is constantly cut off, which makes it very difficult to hear the voice. (2) In the diversity receiver configured as shown in FIG. 11, when antenna selection based on only voice is continued for a long time,
If an antenna with a low image reception level is continuously selected, controls such as AGC in the front end 53 may malfunction and cause detuning or the like. In addition, out-of-synchronization occurs in the image, and the screen becomes difficult to see.

The present invention has been made in consideration of the above problems, and provides a diversity receiving apparatus which does not cause sound interruption, prevents out-of-sync of images, and prevents detuning. The purpose is to provide.

[0008]

In order to achieve the above-mentioned object, the present invention according to claim 1 is provided with a plurality of receiving antennas, and one receiving antenna is selected by combining a video diversity operation and an audio diversity operation. In the diversity receiving device that performs, a changeover switch that changes over a plurality of antennas, an antenna changeover controller that outputs a changeover signal to the changeover switch, a multipath detection circuit that detects a multipath signal from a received audio signal, and a received video signal From the maximum receiving antenna selection circuit for selecting the maximum image electric field level from the, and a video diversity signal for switching to the antenna of the maximum image electric field level of the plurality of antennas during the vertical blanking period based on the vertical synchronizing signal of the video signal. Timing controller and A voice diversity controller is provided, which inputs a path signal and a video diversity signal, and outputs a voice diversity signal for switching a plurality of antennas in a fixed wait time except a vertical blanking period when a multipath signal is detected. To do.

According to a second aspect of the present invention, in the first aspect, the multipath detecting circuit extracts a frequency component which is twice the horizontal synchronizing signal and detects a multipath distortion amount. It is characterized by comprising a second detection circuit for detecting a sharp drop state of the S meter signal.

According to a third aspect of the present invention, in the first aspect, the audio diversity controller includes a first gate circuit for inputting a video diversity signal and a weight signal from the timing controller, and a first gate circuit. And a second gate circuit for inputting the multipath signal from the output and the multipath detection circuit.

[0011]

According to the configuration of the present invention according to claim 1, the timing controller outputs the video diversity signal to the antenna switching controller during the vertical blanking period based on the vertical synchronizing signal of the video signal, and the plurality of antennas The antenna is switched to the antenna with the maximum electric field level of the image selected by the maximum receiving antenna selection circuit. On the other hand, the audio diversity controller inputs the multipath signal and the video diversity signal, outputs the audio diversity signal to the antenna switching controller at a constant wait time when the multipath signal is detected, except for the vertical blanking period, and outputs a plurality of signals. Switch the antennas of. In this case, after waiting for a certain wait time, the multipath signal of the next antenna is detected. By such an operation, it is possible to prevent out-of-synchronization of the image without causing sound interruption, and to prevent detuning or the like.

According to the configuration of the present invention according to claim 2,
The multipath detection circuit includes a first detection circuit for detecting a multipath distortion amount by extracting twice the frequency component of the horizontal synchronization signal, and a second detection circuit for detecting a sudden drop state of the S meter signal. Claim 1 by comprising from Claim 1.
The same operation is performed.

According to the configuration of the present invention according to claim 3,
The audio diversity controller has a first gate circuit for inputting a video diversity signal and a weight signal from the timing controller, and a second gate circuit for inputting an output of the first gate circuit and a multipath signal from the multipath detection circuit. Since it is composed of the gate circuit, the same operation as in claim 1 is performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a diversity receiving apparatus according to the present invention, where 1 is, for example, 4 (1a, 1
b, 1c, 1d), 2 is a changeover switch for arbitrarily changing the four antennas 1a to 1d, and 3 is an intermediate frequency for selecting a desired station from a signal received from any antenna via the changeover switch 2. A front end for converting to (IF) 4, a video IF circuit for extracting and amplifying a video IF signal from the output of the front end 3, 5 a video detection circuit for reproducing a video signal from the output of the video IF circuit 4, and 6 a front An audio IF circuit that extracts the audio IF signal from the output of the end 3 and amplifies it, and outputs the signal of the S meter indicating the received electric field level, 7 is an audio detection circuit that reproduces the audio signal from the output of the audio IF circuit 6, and 8 is Voice I
A multipath detection circuit 10 for detecting a multipath signal from the output of the F circuit 6 and a timing controller 10 for extracting a vertical synchronization signal from the output of the video detection circuit 5 to generate a timing signal (video diversity signal) for antenna switching. An antenna changeover controller that outputs a changeover signal to the changeover switch 2 within the vertical blanking period based on a video diversity signal from the timing controller 10, and a maximum receiving antenna selection circuit 12 that selects the maximum image electric field level from the output of the video detection circuit 5. Is.

Reference numeral 9 is a voice diversity controller,
A voice diversity which inputs a multipath signal from the multipath detection circuit 8 and a video diversity signal from the timing controller 10 and switches a plurality of antennas in a period other than the vertical blanking period with a constant wait time T1 when the multipath signal is detected. The signal (antenna switching signal) is output to the antenna switching controller 11.

FIG. 3 shows a specific structure of the multipath detecting circuit 8. The multipath detecting circuit 8 is composed of a first detecting circuit 14 and a second detecting circuit 15. The first detection circuit 14 includes an amplifier 14A and a comparator 14B.
2f _{H of the} input S meter signal (2f _H :
The frequency component of sub-channel carrier f _H (horizontal synchronizing frequency 15.734 KHz) at the time of audio multiplex broadcasting is extracted by the amplifier 14A as shown in FIG. Is detected and the comparator 1
With the threshold level V _{S of} 4B as the detection level,
Generates antenna switching signal. The second detection circuit 15 has a comparator 15A and detects skip noise based on the input S meter signal. One of the comparators 15A has an offset level set by resistance voltage division and an integration by capacitance. By giving an operation, a sudden drop state of the S meter signal is detected as shown in FIG.

FIG. 5 shows a voice diversity controller 9
The audio diversity controller 9 includes a video diversity signal (a) from the timing controller 10 and a constant wait time T.
A first gate circuit 16 for inputting a wait signal (c) from a timer 15 for giving 1, and the first gate circuit 1
The second gate circuit 1 for inputting the output of 6 and the multipath signal (b) from the multipath detection circuit 8 and outputting the antenna switching signal (d) which functions as a voice diversity signal.
7 and 7. FIG. 6 shows a timing chart of the signals (a) to (d).

FIG. 7 shows a specific configuration of the antenna switching controller 11. This antenna switching controller 11 stores the antenna in which the image maximum electric field level selected by the maximum receiving antenna selection circuit 12 is obtained. Latch 14 and timing controller 1
Counter 1 that sequentially counts its antennas under the control of 0
It is composed of 5 and.

FIG. 8 shows the concrete contents of the maximum receiving antenna selection circuit 12, and this maximum receiving antenna selection circuit 12 has a comparator 12A. 9A to 9D are timing charts for explaining the operation. (A) shows a part of the video signal when the video diversity operation is not performed (vertical blanking period is 10H, for example), and (b) shows a part of the video signal when the video diversity operation is performed, The waveform has an irregular shape corresponding to the electric field level, and the higher the electric field level, the more concave the waveform. In the case of this example, the magnitude relationship of the electric field level is
<<<< That is, an example in which the third antenna 1c has the highest electric field level is shown. (C) shows the selected antenna number in the case of (a). That is, it indicates that the first antenna 1a was selected before the image diversity operation and the third antenna 1c was selected after the image diversity operation.
(C) shows the maximum detection number output to the antenna switching controller 11. That is, it indicates that the signal corresponding to the antenna 1c having the highest electric field level is detected.

As is clear from the configuration of FIG. 3, the multipath detection circuit 8 has a state transition time mainly due to the capacitive component in the circuit, so that the multipath is switched to the antenna switched by the detection of the multipath signal. Even if it does not exist, the multipath signal is output for a certain period of time after switching, assuming that there is multipath and that the multipath signal is detected. For this reason, the timer 15 is provided as shown in FIG. 5 until the next antenna multipath judgment is made after switching, and the wait signal (c) having the wait time T1 of a constant time is provided to the first gate circuit 16. In addition to this output, the multipath signal (b) is added to the second gate circuit 17 to output the antenna switching signal (antenna feed signal) (d) that functions as a voice diversity signal to the antenna switching controller 12. I have to.

In addition, as shown in FIG. 9, the video diversity operation is performed by switching all four antennas 1a to 1d in a specific 1H section in the vertical blanking period and comparing the received electric field levels. The antenna with a high level is selected by the maximum receiving antenna selection circuit 12, but in this process, the S-meter output of the voice when switching to the antenna with a low electric field level is lowered, and the multipath detection circuit 8 malfunctions. Then, the multipath signal may be detected. In order to prevent this, a signal indicating this is output during video diversity operation, and antenna switching by multipath is stopped during this period.

Next, the operation of this embodiment will be described. The timing controller 10 outputs a video diversity signal, which is a timing signal, to the antenna switching controller 11 during the vertical blanking period based on the vertical synchronizing signal of the received video signal. Based on this, the antenna selector controller 11 outputs a selector signal to the selector switch 2,
Four antennas 1a to 1d within the vertical blanking period
Are sequentially switched. Now, before switching, as shown in FIG.
It is assumed that the th antenna 1a has been selected and connected. As a result of comparing the respective electric field levels by sequentially switching the four antennas 1a to 1d, as shown in FIG.
If the relation <<<< is met, the maximum receiving antenna selection circuit 12 selects the third antenna 1c and outputs this to the antenna switching controller 11 as the maximum detection number. Based on this, the antenna changeover controller 11 outputs a changeover signal to the changeover switch 2 under the control of the timing controller 10. As a result, the changeover switch 2 selects and connects the third antenna 1c, so that the image reception by the antenna 1c is continued until the next vertical blanking period.

During such video reception, a multipath signal is detected by the multipath detection circuit 8 and the audio diversity signal is output to the antenna switching controller 11 via the audio diversity controller 9 as shown in FIG. Based on this, the antenna selector controller 11 outputs a selector signal to the selector switch 2. As a result, the currently receiving antenna 1c is switched to another antenna. When the antennas are switched, multipath determination is performed by the switched antennas. As described above, the determination of this multipath is made by the wait time T of a certain time.
It is performed based on the weight signal having 1. When a multipath signal is detected by the switched antenna, switching to the next antenna is performed in the same manner, and the switching operation is repeated until the multipath signal is no longer detected. As described above, such a switching operation is performed between a vertical blanking period which avoids the vertical blanking period and another vertical blanking period so as not to affect the video diversity operation.

As described above, according to this embodiment, in the vertical blanking period based on the vertical synchronizing signal of the received video signal, the antenna having the maximum video electric field level of the plurality of antennas is combined with the video diversity operation. Then, the voice multipath signal is detected in a certain wait time, and the voice diversity operation of sequentially switching the antennas is performed until the multipath signal is no longer detected. Therefore, the following effects can be obtained. (1) Even when multipaths are frequently generated, a plurality of antennas are sequentially switched until the multipaths are no longer detected, so that sound interruption does not occur, so that it is not difficult to hear voice. (2) Since the antenna selection based only on the voice does not continue for a long time, the antenna with the low video reception level does not continue to be selected.
It does not cause detuning, etc. without causing malfunction of controls such as. In addition, since out-of-synchronization does not occur even in video, the screen is not difficult to see. The number of antennas can be set as needed.

FIG. 2 is a block diagram showing a modified example of the diversity receiving apparatus of the present embodiment. In particular, when the speed of the moving body is stopped or low, the antenna selection by the multipath state of voice is stopped. Then, an example is shown in which the antenna selection is performed only by the electric field level of the image. In FIG. 2, 1 is, for example, 4 (1a, 1
b, 1c, 1d), 2 is a changeover switch for arbitrarily changing the four antennas 1a to 1d, and 3 is an intermediate frequency for selecting a desired station from a signal received from any antenna via the changeover switch 2. The front end 4 for converting to (IF) is an image I from the output of the front end 3.
A video IF circuit that extracts and amplifies the F signal, and 5 is a video I
A video detection circuit for reproducing a video signal from the output of the F circuit 4,
Reference numeral 6 is an audio IF circuit for extracting and amplifying an audio IF signal from the output of the front end 3 and outputting an S-meter signal indicating the received electric field level. Reference numeral 7 is an audio detection circuit for reproducing an audio signal from the output of the audio IF circuit 6. , 8 is a multipath detection circuit for detecting a multipath signal from the output of the audio IF circuit 6, and 10 is a timing for extracting a vertical synchronization signal from the output of the video detection circuit 5 to generate an antenna switching timing signal (video diversity signal). controller,
Reference numeral 11 is an antenna selector controller that outputs a switching signal to the selector switch 2 within the vertical blanking period based on the video diversity signal from the timing controller 10, and 12 is a maximum receiving antenna that selects the video maximum electric field level from the output of the video detection circuit 5. It is a selection circuit.

Reference numeral 18 inputs the velocity signal of the moving body to select an antenna by voice and image when the moving body moves at high speed, and selects an antenna only by image when the moving body is stopped or moving at low speed. A voice diver on / off determination circuit for outputting a switching signal, and a switching switch 19 for switching the output from the multipath detection circuit 8 to the antenna switching controller 11 by the voice diver on / off determination circuit 18. The voice diver controller 9 shown in FIG. 1 may be provided either before or after the switch 19. The speed signal may simply use a parking signal.

According to such a configuration, when the moving body is in a traveling state, the changeover switch 19 is connected so as to send the output of the multipath detecting circuit 8 to the antenna changeover controller, whereby voice and When the antenna is selected by the image and the moving body is in a stopped state or at a low speed, the voice diver on / off determination circuit 18 detects it, and the changeover switch 19 is changed over by the changeover signal, thereby changing the voice multipath state. The antenna selection can be stopped and the antenna selection can be performed only by the electric field level of the image.

As a result, during traveling in which information of the television broadcast is mainly obtained by voice, antenna selection by voice and image is performed, and in addition, information is obtained from the screen. It becomes possible to obtain an easy-to-see screen that does not have any That is, it is possible to obtain a stable image and sound without causing noise, distortion, or sound interruption in the sound both when the vehicle is running and when the vehicle is stopped.

[0029]

As described above, according to the present invention, a multipath signal of voice is detected in a constant wait time by combining with the video diversity operation for selecting the antenna having the maximum video electric field level among a plurality of antennas. Since the audio diversity operation is performed by sequentially switching the antennas until the multipath signal is no longer detected, sound interruption does not occur, out-of-sync of the image is prevented, and detuning etc. does not occur. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a diversity receiver of the present invention.

FIG. 2 is a block diagram showing a modified example of the present embodiment.

FIG. 3 is a circuit diagram showing a specific configuration of a multipath detection circuit of the diversity receiver of this embodiment.

FIG. 4 is a characteristic diagram illustrating an operation of the multipath detection circuit of FIG.

FIG. 5 is a block diagram showing a specific configuration of a voice diversity controller of the diversity receiver of this embodiment.

6 is a timing chart explaining the operation of the audio diversity controller of FIG.

FIG. 7 is a block diagram showing a specific configuration of the antenna switching controller of this embodiment.

FIG. 8 is a circuit showing a specific configuration of a maximum receiving antenna selection circuit of this embodiment.

9 is a timing chart illustrating the operation of the maximum receiving antenna selection circuit of FIG.

FIG. 10 is a block diagram showing an example of a conventional diversity receiver.

FIG. 11 is a block diagram showing another example of a conventional diversity receiver.

12 is a block diagram showing a specific configuration of the antenna switching controller of FIG.

[Explanation of symbols]

 1, 1a to 1d Reception antenna 2 Changeover switch 3 Front end 9 Multipath detection circuit 10 Timing controller 11 Antenna changeover controller 12 Maximum reception antenna selection circuit 14 First detection circuit 15 Second detection circuit 16 First gate circuit 17 Second gate circuit 18 Audio diver on / off determination circuit

Claims (3)

[Claims] 1. A diversity receiving apparatus having a plurality of receiving antennas, wherein one receiving antenna is selected by combining a video diversity operation and an audio diversity operation, and a changeover switch for changing over the plurality of antennas and a changeover switch. An antenna switching controller that outputs a signal, a multipath detection circuit that detects a multipath signal from a received audio signal, a maximum reception antenna selection circuit that selects a video maximum electric field level from the received video signal, and a vertical direction of the video signal. A timing controller that outputs a video diversity signal that switches to an antenna having the maximum image electric field level among a plurality of antennas in a vertical blanking period based on a synchronization signal, and inputs the multipath signal and the video diversity signal, and outputs the multipath signal. detection And a voice diversity controller which outputs a voice diversity signal for switching a plurality of antennas in a constant wait time during periods other than the vertical blanking period, and a diversity receiver. 2. A first detection circuit for detecting the amount of multipath distortion by extracting twice the frequency component of the horizontal synchronizing signal and a first detection circuit for detecting a sudden drop state of the S meter signal. 2. The diversity receiving device according to claim 1, wherein the diversity receiving device comprises two detection circuits. 3. The audio diversity controller outputs a first gate circuit for inputting a video diversity signal and a weight signal from the timing controller, an output of the first gate circuit and a multipath signal from a multipath detection circuit. The diversity receiving device according to claim 1, wherein the diversity receiving device comprises an input second gate circuit.